Siemens manufactured mass air flow sensor -

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Up for sale is a good working Airflow Meter that should fit many BMW models.

This may even fit other models/years not in this range, but as always its your best bet to match the part number with the original one in your car. This unit is from a recent crash damaged car.  This unit is an original manufacturer part!  Not aftermarket.  offers a 30 day warranty. This is a VERY hard to find part.   You can often find air flow meters made by aftermarket brands (cheap china made components) that often do not function properly, meter air improperly which causes drivability problems and may cause check engine lights.  Get a good used original part here, you are far better off!

A bad AMM can cause a lean running condition, loopy idle, no start, runs but has no power, random stalling, excess smoke, pinging, or any other strange running conditions.